Coolant systems provide a mechanism for heat transfer between engine components and a heat transfer fluid. Historically, coolant systems have been used to decrease the temperature of an engine block, however, systems have advanced over the years and the desire for temperature control of engine components, beyond cooling, exist. For example, it may be advantageous to heat the engine and/or other engine components during an engine start, but cool the engine and components during high load conditions. Further, the engine may have different heating and/or cooling demands than other engine components.
In order to satisfy this demand, dual loop coolant systems have been introduced and generally contain a high temperature coolant loop and a low temperature coolant loop to manage the temperature of system components. It is advantageous to properly separate the high temperature coolant from the low temperature coolant, otherwise, temperature control of the engine components is compromised. Maintaining the coolant loops separately may present a challenge when both loops feed into a common heat exchanger, such as a transmission oil cooler. Methods and systems exist to address separation of high temperature coolant from low temperature coolant, however, the inventors herein have recognized potential issues with such systems. Dual loop coolant systems may use multiple electronic valves to direct high temperature coolant or low temperature coolant to a common heat exchanger. However, this method is not robust against an operational failure or a system failure where the coolant from the two loops may mix. In addition, these systems are complex and expensive.
As an example, the issues described above may be addressed by a method for a dual loop coolant system with a high temperature coolant loop separated from a low temperature coolant loop. The high temperature coolant loop has a first heat exchanger and the low temperature coolant loop has a second heat exchanger. A control valve is positioned upstream of the first heat exchanger to direct flow of an engine coolant to the first heat exchanger. A bypass valve exists between the first heat exchanger and the second heat exchanger to control flow of an engine component fluid between the two heat exchangers. An engine component is fluidically coupled to the first heat exchanger, the bypass valve, and the second heat exchanger. In this way, the likelihood of the high temperature coolant mixing with the low temperature coolant is reduced.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.